Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ch. XVIII.] WEALDEN GROUP. 349 The picturesque scenery of the ' High Rocks ' and other places in the neighborhood of Tunbridge is caused by the steep natural cliffs, to which a hard-be of white sand, occurring in the upper part of the Tunbridge 'Wells Sand, mentioned in the preceding table, gives rise. Mr. Drew found this bed of ' rock-sand ' to vary in thickness from 25 to 48 feet. Large masses of it, which were by
Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ch. XVIII.] WEALDEN GROUP. 349 The picturesque scenery of the ' High Rocks ' and other places in the neighborhood of Tunbridge is caused by the steep natural cliffs, to which a hard-be of white sand, occurring in the upper part of the Tunbridge 'Wells Sand, mentioned in the preceding table, gives rise. Mr. Drew found this bed of ' rock-sand ' to vary in thickness from 25 to 48 feet. Large masses of it, which were by no means hard or capable of making a good building-stone, form, nevertheless, project- ing rocks with perpendicular faces, and resist the degrading action of the river because, says Mr. Drew, they present a solid mass with- out planes of division.* The calcareous sandstone and grit of Til- gate Forest near Cuckfield, in which the remains of the Tguanodon and Hylseosaurus were first found by Dr. Mantell, constitute an upper member of the Tunbridge 'Wells Sand, while the ' sand-rock ' of the Hastings cliffs, about 100 feet thick, is one of the lower members of the same. The reptiles, which are very abundant in this division, consist partly of saurians, referred by Owen and Mantell to eight genera, among which, besides those already enumerated, we find the Megalosaurus and Ple'siosaurus. The Pterodactyl also, a flying rep- tile, is met with in the snme strata, and many remains of Chelonians of the genera Trionyx and Emys, now confined to tropical regions. The fishes of the Wealden are chiefly referable to the Ganoid and Placoid orders. Among them the teeth and scales of Lepidotus are most widely diffused (see fig. 343). These ganoids were allied to the Fig. 848. » Zepidotus JfanteUi, Agass. Wealden. a. Palate and teeth. 6. Side view of teeth. c. Scale. Lepidosteus, or Gar-pike, of the American rivers. The whole body was covered with large rhomboidal scales, very thick, and ha
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